414 DISEASES OF CATTI^. 



most likely to prove successful. The measures which are adopted to 

 this end can not be discussed in this place, but it is a striking fact 

 that where the muzzling of all dogs has been rigidly enforced, as in 

 England and in certain German districts, the disease has been prac- 

 tically stamped out. 



TUBERCULOSIS. 

 (Plates XXIX, flg. 6; XXXIV to XL, Inclusive.) 



Tuberculosis is an infectious and communicable disease charac- 

 terized by the formation in various organs of the body of minute 

 nodules or tubercles, which contain the Bacillus tuberculosis, the 

 cause of the disease. 



The disease, in its various manifestations, has been known for many 

 centuries, and legislative enactments having reference to the destruc- 

 tion of affected animals and forbidding the use of the flesh date far 

 back into the middle ages. The opinions entertained regarding the 

 nature and the cause of the malady varied much in different periods 

 and very markedly influenced the laws and regulations in vogue. 

 Thus, in the sixteenth century, the disease was considered identical 

 with syphilis in man. In consequence of this belief very stringent 

 laws were enacted, which made the destruction of tuberculous cattle 

 compulsory. In the eighteenth century this erroneous conception 

 of the nature of the disease was abandoned and all restrictions against 

 the use of meat were removed. Since that time, however, the com- 

 municable nature of this disease has been established by many inves- 

 tigators, and the tide of opinion has again turned in favor of repress- 

 ing the disease and prohibiting the sale of contaminated products. 



Occurrence. — The statistics concerning tuberculosis show that it is 

 a disease prevalent in all civilized countries. In some countries, such 

 as the northern part of Norway and Sweden, on the steppes of eastern 

 Europe and Russia, in Sicily and Iceland, and in Algiers, it is said 

 to be quite rare. 



The returns from testing British cattle with tuberculin, supplied by 

 the Royal Veterinary College, as stated in March, 1900, showed that 

 among 15,392 animals tested 4,105, or 26 per cent, reacted. 



During the slaughter of cattle for pleuropneumonia careful exami- 

 nations of the carcasses were made for tuberculosis. Of 300 head 

 killed near Edinburgh 120, or 40 per cent, were tuberculous. Of 

 4,160 killed in England 20 per cent were tuberculous. Of one of 

 these lots of cattle (451 animals) the president of the Lancashire 

 Farmers' Association testified that they were fairly representative 

 cattle — cows, heifers, and growing stock — a thoroughly mixed lot; 

 20 per cent of these animals had tuberculosis. 



